Page 153 of 384

Parking Brake Warning Light
Your vehicle has a brake warning light. When the
ignition is on, this light will come on when you set your
parking brake. The light will stay on if your parking
brake does not release fully.
This light should also come on when you turn the
ignition key to START. If it does not come on then, have
it fixed so it will be ready to remind you if the parking
brake is applied or has not released fully.
Air Brake System Warning Light
Vehicles with air brake systems have a brake system
warning light on the instrument panel.
The low air warning light
should come on, as a
check, whenever you start
the engine.
However, it is designed to come on, and stay on, when
brake reservoir pressure has dropped below 60 psi
(410 kPa).When the warning light comes on while you are driving,
you should drive only as far as the nearest point of
safety and then stop the vehicle. Here is a very
important thing for you to know:
{CAUTION:
If the air brake system warning light comes on
and the warning tone sounds, the vehicle can
stop suddenly and without further warning.
This is because the parking brake will come on
if the pressure falls below 35 to 45 psi (240 to
310 kPa). You or others could be injured. If the
air brake system warning light comes on and
the warning tone sounds, stop as soon as you
can. You will not know how quickly the system
is losing pressure, so be aware that the
parking brake may come on suddenly.
3-33
Page 154 of 384

Anti-lock Brake System (ABS)
Warning Light
This light will come on
briefly when you start the
engine, then it will turn
off. This is normal.
If the light stays on, or comes on when you are driving,
your vehicle needs service. If the brake or low air
warning light is not on, you still have brakes, but you do
not have the antilock brake feature. If the brake
and/or low air warning light is on, you do not have
antilock brakes and there is a problem with your regular
brakes. SeeBrake System Warning Light on page 3-32
andAntilock Brake System (ABS) on page 4-5for
more information.
Trailer Antilock Brake System
Warning Light
If your vehicle is connected
to a trailer with antilock
brakes, this light should
come on briefly, as a
check, when you turn on
the ignition.
When this light comes on and stays on, it means there
is something wrong in the trailer Antilock Brake
System (ABS). Have the system repaired immediately.
If an ABS equipped trailer is not connected, this
light is not functional.
3-34
Page 155 of 384

Engine Coolant Temperature Gage
This gage shows the
engine coolant
temperature. If the gage
pointer moves into the
red area, your engine
coolant might have
overheated and your
engine may be too hot.
You should pull off the road, stop your vehicle and turn
off the engine as soon as possible.
SeeEngine Overheating on page 5-48. If you have a
Caterpillar
®diesel engine, also see your Caterpillar®
Operation & Maintenance Manual.
Low Coolant Warning Light
Your vehicle has a low
coolant warning light.
If this light comes on, the
system is low on coolant
and the engine may
overheat.
The warning light should come on briefly, as a check,
when you turn on the ignition.
When it comes on, you will also hear a warning tone for
10 seconds. SeeEngine Coolant (Caterpillar
®Diesel
Engines) on page 5-44orEngine Coolant (Gas and
DURAMAX
®/Isuzu 7.8L L6 Engines) on page 5-44
Engine Coolant and have your vehicle serviced as
soon as you can.
This light may also come on if your vehicle has the
automatic engine shutdown system and engine
shutdown has begun. SeeEngine Alarm and Automatic
Shutdown on page 2-18for more information.
3-35
Page 156 of 384

Wait to Start Indicator
If your vehicle has the DURAMAX®6.6L diesel engine,
it will have glow plugs and an air intake heater.
If your vehicle has the Isuzu 6H diesel engine, it will
have glow plugs and an inlet heater. If your vehicle has
a Caterpillar
®engine, it will have an inlet heater.
The light in the center of
the instrument panel will
come on when the
inlet heater or glow plugs
are on and the ignition
key is in RUN.
Wait until the indicator light goes off before turning the
ignition key to START.
Malfunction Indicator Lamp
Service Engine Soon Light
If this light comes on or
flashes while you are
driving, two things
can happen.
First, you will not notice any difference in engine
performance, but the tail pipe emissions might increase.
Second, the engine might not run properly or could stall
without warning. If either of these things happen, drive or
tow your vehicle to your dealer/retailer for service.
This light should come on when the ignition is on, but the
engine is not running, as a check to show you it is
working. If it does not come on at all, have it repaired.
Notice:If you keep driving your vehicle with this
light on, after a while, the emission controls
might not work as well, your vehicle’s fuel economy
might not be as good, and the engine might not
run as smoothly. This could lead to costly repairs
that might not be covered by your warranty.
3-36
Page 157 of 384

Oil Pressure Gage
The engine oil pressure
gage, on the lower right
portion of your instrument
panel cluster, shows
engine oil pressure in
psi (pounds per square
inch) or in kPa
(kilopascals).
Oil pressure may vary with outside temperature and oil
viscosity, but readings of 30 to 40 psi (205 to 275 kPa)
on gasoline engines at operating temperature and
moderate road speeds are normal. If you have a diesel
engine, the normal operating range should be between
35 and 70 psi (240 to 480 kPa).A reading in the low pressure zone may be caused by a
dangerously low oil level or other problem.
If you have a Caterpillar®diesel engine, also see your
Caterpillar®Operation & Maintenance Manual.
{CAUTION:
Do not keep driving if the oil pressure is low.
If you do, your engine can become so hot that
it catches re. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
Notice:Lack of proper engine oil maintenance
may damage the engine. The repairs would not be
covered by your warranty. Always follow the
maintenance schedule in this manual for changing
engine oil.
3-37
Page 158 of 384

Low Oil Level Light
Your vehicle may have a
low oil level light.
This light should come on as a check, when you start
your engine. If the light fails to come on, have it repaired
as soon as possible so you will be aware when the oil
level is low.
Vehicles that have Caterpillar
®diesel engines may not
have a low oil level light. In this case, the light will
neither come on as a check when you start your engine,
nor will it come on to indicate a low oil level.
If this light comes on and stays on, it means your
engine is low on oil. You need to check the oil level
right away. SeeEngine Oil (Caterpillar
®Diesel Engine)
on page 5-23orEngine Oil (Gasoline Engine) on
page 5-24orEngine Oil (DURAMAX
®Diesel Engine) on
page 5-28orEngine Oil (Isuzu Diesel Engine) on
page 5-32for further information.
Notice:Lack of proper engine oil maintenance may
damage the engine. The repairs would not be covered
by your warranty. Always follow the maintenance
schedule in this manual for changing engine oil.
Change Engine Oil Light
The change engine oil light
should come on briefly as
a bulb check when you
start the engine. If the light
does not come on, have
it serviced.
If the change engine oil light comes on and stays on
after you start the engine, have the oil changed.
For additional information on when to change engine oil
for gasoline engines or DURAMAX
®diesel engines,
seeEngine Oil (Caterpillar®Diesel Engine) on page 5-23
orEngine Oil (Gasoline Engine) on page 5-24or
Engine Oil (DURAMAX
®Diesel Engine) on page 5-28or
Engine Oil (Isuzu Diesel Engine) on page 5-32and
Scheduled Maintenance on page 6-5. To reset the
change engine oil light, seeEngine Oil Life System
(Gasoline Engine) on page 5-36orEngine Oil Life
System (DURAMAX
®/Isuzu Diesel Engines) on
page 5-37orEngine Oil Life System (Caterpillar®Diesel
Engine) on page 5-39.
3-38
Page 159 of 384

Engine Overspeed Warning Light
If your vehicle has this
light, it will come on if your
engine is operating at
too many revolutions per
minute (rpm).
It will also come on for a moment as a check when you
start your engine.
If it comes on when you’re driving, reduce your engine
speed immediately.
Engine Shutdown Warning Light
If your vehicle has the
engine shutdown feature,
this light will come on
when engine shutdown
is active.
SeeEngine Alarm and Automatic Shutdown on
page 2-18for more information.
Transmission Temperature Gage
If you have an automatic
transmission and this
gage, it is located
above the switchbank
in the center of the
instrument panel.
When your ignition is on, the gage shows the
temperature of the transmission oil. A reading in the
warning zone, the red area beginning at 300°F (150°C),
means you must stop driving and check into the cause.
One possible cause is a low oil level in the transmission.
Notice:If you drive your vehicle with the
transmission temperature gage above normal
operating range, you can damage the transmission.
This could lead to costly repairs that would not
be covered by your warranty. Do not drive your
vehicle while the transmission temperature gage
reading is above normal. See your dealer for service.
3-39
Page 160 of 384
Exhaust Brake Indicator Light
For vehicles with an
exhaust brake, this light is
located above the
climate controls.
The exhaust brake indicator light will come on and stay
on whenever the diesel engine exhaust brake or
exhaust restrictor is active. For more information,
seeDiesel Engine Exhaust Brake on page 2-26and
Exhaust Restrictor (Engine Warm-Up) on page 2-22.
Differential Lock Indicator Light
If your vehicle has this
feature, this light is
located in the center of
the instrument panel.
The light is on when the
rear differential lock system
is in use.
The light will come on momentarily during starting.
If the light fails to come on, have it repaired as soon as
possible so you will be aware when the lock system
is in use.
SeeRear Axle Differential Lock Control on page 4-7for
more information.
3-40